This invention relates to reactive azo dyes containing each of a triazine ring and at least one reactive vinyl sulphone group (or precursor thereof) and at least two azo groups. Such dyes are disclosed in, for example, EP-A-0623655, EP-A-0685532 and EP-A-076469 and typical dyes are as follows: 


However, none of the dyes disclosed in the abovementioned documents provide a particularly strong or bright yellow or reddish yellow shade with good migration properties, excellent build-up and good fastness properties.
Thus, the problem addressed by the invention is to provide such a dye capable of giving, particularly on cellulosic fabrics, a strong, bright yellow or reddish yellow shade with good migration properties, excellent build-up and which dyes are particularly easy and economical to produce.
We find surprisingly that it is possible to solve the abovementioned problems by the use of an azo dye containing, on the one hand, a monoazo dye component based on sulpho-J-acid as coupling component and a markedly electron deficient aromatic amine as diazo component and, on the other hand, an azo dye component containing each of a phenylene group and an aromatic group or hetero aromatic group, each dye component being linked, via an amino linkage to a triazine group, the second dye component being so linked via the phenylene group.
Thus, according to one aspect the invention provides an azo dye of the formula (I) 
or an alkali metal salt thereof:
wherein: each of R1 and R2 independently is hydrogen, optionally substituted C1-4 alkyl or optionally substituted phenyl;
A is 
in which formula (i), c is zero or 1;
in which formula (ii), d is 1, 2 or 3 and a group SO3H is ortho to the azo group; and
in which formula (i) or (ii), Y is the group xe2x80x94CHxe2x95x90CH2; xe2x80x94CH2CH2U (wherein U is a leaving group); or xe2x80x94CH2CHxe2x95x90CH2;
B is fluorine; chlorine; the group OR3 (in which R3 is hydrogen, C1-4 alkyl or phenyl); the group NR4R5 (in which each of R4 and R5 independently is hydrogen, C1-4 alkyl or phenyl; or each of R4, R5 and N together form an optionally substituted aromatic heterocyclic ring); the group +NR6R7R8 (in which each of R6, R7 and R8 independently is C1-4 alkyl or phenyl or each of R6, R7 and R8 and N together form an optionally substituted aromatic heterocylcic ring); or the group SR9 (in which R9 is hydrogen, C1-4 alkyl or phenyl);
C is an optionally substituted aromatic or heteroaromatic residue;.
D is methyl, methoxy, amino, acylamino or ureido;
a is zero, 1 or 2;
b is zero, 1 or 2 and when b is 2 each D is independent of the other.
Preferably, the substituent D is methyl, methoxy, acylamino or ureido and the substituent B is preferably chlorine or a 3- or 4- carboxypyridinium salt derived respectively from nicotinic and isonicotinic acid.
In the above dye, the group A preferably has the formula 
wherein e is xe2x80x94SO2CH2CH2OSO3H and f is absent; or
e is xe2x80x94SO3H and f is xe2x80x94SO2CH2CH2OSO3H.
A preferred azo dye has the formula 
wherein each of R2, C, D a, b, e and f is as defined above.
More preferably in the azo dye of the formula (I1), at least one of the groups SO3H or D is ortho to the azo group linking to the group C.
In one range of dyes of the formula (I1) which is preferred, a is 1 or 2 and b is zero. More preferably, the group C is a heteroaromatic group, still more preferably a pyridonyl, pyrazolonyl, 2,6-diaminopyridinyl or 4-carboxy-2,6-dihydroxypyridinyl group, or is a hydroxynaphthalene group.
In another range of dyes of the formula (I) which is preferred a is zero or 1, b is 1 or 2 and D, or each D independently, is ureido, (C1-4 alkyl)carbonylamino, C1-4 alkoxy or C1-4 alkylthio.
For such dyes within this other range, a preferred group C has the formula (iv) 
wherein : Ar1 is an aromatic diazo component;
g is zero, 1, 2, 3 or 4;
h is zero, 1, 2 or 3; and
P, or each P independently, is C1-4 alkyl, nitro, xe2x80x94SO2NR8 (in which R8 is hydrogen, C1-4 alkyl or phenyl), carboxyl, cyano, SO2Y1 (in which Y1 is vinyl, allyl or CH2CH2V, where V is a leaving grup) or xe2x80x94NHAr2 [in which Ar2 is an aromatic residue substituted by at least one group T, the group T, or each group T independently, being selected from cyano, carboxyl, sulphonic acid and SO2Y2 (in which Y2 is vinyl, allyl or CH2CH2W (where W is a leaving group)].
More preferably, at least one group P is a group SO2Y1, where Y1 is as defined above or a group NHAr2 substituted by a group T, which group T is the group SO2Y2, in which Y2 is as defined above.
Preferred values of Y1 and Y2 independently are xe2x80x94CHxe2x95x90CH2; xe2x80x94CH2xe2x80x94CHxe2x95x90CH2; xe2x80x94CH2CH2Cl, xe2x80x94CH2CH2Br; xe2x80x94CH2CH2F; xe2x80x94CH2CH2OSO3H; xe2x80x94CH2CH2SSO3H; xe2x80x94CH2CH2OCOCH3, xe2x80x94CH2CH2OPO3H2; xe2x80x94CH2CH2OCOC2H5; xe2x80x94CH2CH2OSO2NR9 (in which R9 is hydrogen, C1-4 alkyl or phenyl); and xe2x80x94CH2CH2OSO2R10 (in which R10 is hydrogen, C1-4 alkyl or phenyl).
Most preferably C is the group 
Typical azo dyes embodying the invention have the formula 
wherein Z is selected from 
Another typical azo dye embodying the invention has the formula 
An azo dye of the formula (I), given and defined above may be prepared by a process which comprises reacting a triazine dye of the formula (II) 
wherein each of R1, A and B is as defined above and Hal is a halogen atom;
with an azo dye of the formula (III) 
wherein each of a, b, R2, C and D is as defined above.
The process is preferably carried out in an aqueous solution at pH 4-6 and at a temperature of at least 30xc2x0 C.
The triazine dye of the formula (II) may be prepared by diazotising an amine of the formula (IV)
Axe2x80x94NH2xe2x80x83xe2x80x83(IV)
wherein A is as defined above and coupling the diazotised amine of the formula (IV) to a triazine compound of the formula (V) 
wherein each of R1 and B is as defined above and Hal is a halogen atom, to obtain the triazine dye of the formula (II).
Typically, diazotisation of the amine is carried out in an acid medium at a pH of about 2-5, using, for example, acetic, propionic or hydrochloric acid in the presence of a nitrosating agent, such as nitrosyl sulphuric acid, an alkali metal nitrite (e.g sodium nitrite) or a C1-4 alkyl nitrite (e.g. methyl nitrite) at a temperature of from xe2x88x9210xc2x0 C. to 10xc2x0 C.
The coupling reaction may be carried out by adding the diazotised amine of the formula (IV), to the triazine compound of the formula (V) in water at a temperature of from 0 to 10xc2x0 C.
The triazine compound of the formula (V), given and defined above, may be prepared by reacting an aminonaphthalenesulphonic acid compound of the formula (VI) 
with a cyanuric halide of the formula (VII) 
wherein each Hal is a halogen atom and B is as defined above, to form the triazine compound of the formula (V).
The reaction may be carried out by adding the aminonaphthalene sulphonic acid compound of the formula (VI) dropwise to a slurry of the cyanuric halide of the formula (VII) in an ice/water/acetone mixture.
When in the azo dye of the formula (III), a is 1 or 2, b is zero and C is the residue of a heteroaromatic coupling component the azo dye of the formula (III) may be prepared by acylating a diamine of the formula (VIII) 
where a is zero, 1 or 2 to form an amine of the formula (IX), 
where a is zero, 1 or 2 and Ac is an acyl group, diazotising the amino of the formula (IX) and coupling the diazotised amine to a coupling agent of the formula
Cxe2x80x94H
xe2x80x83where C is as defined above to form, after deacetylation, the azo dye of the formula (III).
When, in the azo dye of the formula (III), a is zero or 1, b is 1 or 2 and D, or each D independently, is ureido, (C1-4 alkyl)carbonyl amino, C1-4 alkoxy or C1-4 alkylthio and the Group C is a group (iv) 
wherein each of Ar1, P, g, and h is as defined above, the azo dye of the formula (III) may be prepared by diazotising an amine of the formula (X) 
wherein each of Ar1, P, g and h is as defined above, and coupling the diazotised amine with a coupling agent of the formula (XI) 
xe2x80x83where D is as defined above, a is zero or 1 and b is 1 or 2.
In either of the above reactions, the diazotisation and coupling may be carried out in a manner analogous to that described in relation to the preparation of the triazine dye of the formula (II).
Dyes embodying the invention may be applied alone or in admixture with other dyestuffs.
Although in this specification, dye formulae have been shown in the form of their free acid, the invention also includes dyes and processes using dyes in the salt form, particularly their salts with alkali metals such as the potassium, sodium, lithium or mixed sodium/lithium salt.
The dyes may be used for dyeing, printing or ink-jet printing, for example of textile materials and paper.
The process for colouration is preferably preformed at a pH of 7.1 to 13, more preferably 10 to 12 pH levels above 7 can be achieved by performing the process for colouration in the presence of an acid-binding agent. They can be applied at any temperature from room temperaure (e.g. 15xc2x0 C.) to 80xc2x0 C., preferably from 40 to 60xc2x0 C.
The substrate may be any of fibre material such as a textile material, leather, paper, hair or film, but is preferably a natural or artifiical textile material containing amino or hydroxyl groups, for example textile material such as wool, silk, polyamides and modified polyacrylonitrile fibres, and more preferably a cellulose, for example, that commercially available as Tencel. For this purpose the dyes can be applied to the textile materials at a pH above 7 by, for example, exhaust dyeing, padding or printing. Textile materials are coloured bright shades and possess good fastness to light and wet treatments such as washing.
The new dyes are particularly valuable for colouring cellulosic textile materials. For this purpose, the dyes are preferably applied to the cellulosic textile material at a pH above 7 in conjunction with a treatment with an acid-brinding agent.
Preferred acid-binding agents include alkali metal carbonates, bicarbonates, hydroxides, metasilicates and mixtures thereof, for example sodium bicarbonate, sodium carbonate, sodium metasilicate, sodium hydroxide and the corresponding potassium salts. The dyes benefit from excellent build-up and high fixation.
The new dyes can be applied to textile materials containing amine groups, such as wool and polyamide textile materials, from a neutral to mildly alkaline dyebath. The dyeing process can be carried out at a constant or substantially constant pH, that it to say the pH of the dyebath remains constant or substantially constant during the dyeing process, or if desired the pH of the dyebath can be altered at any stage of the dyeing process.
The dyes may be in liquid or solid form, for example in granular or powdered form.
According to yet another aspect of the invention there is provided a process for colouring a fibre material containing a group reactive with a reactive dye or a fibre blend containing the fibre material, which method comprises applying thereto a dye of the formula (I), given and defined above, preferably at a pH above 7.
Preferred embodiments of the invention will now be described in more detail with reference to the following Examples, in which all parts are by weight unless otherwise stated.